Vacuum tube and mounting



March 22, E, MARSHALL 1,850,559

VACUUM TUBE AND MOUNTING Filed April 21, 1928 25 1 y l g: 15 6 23INVENTOR TTORNIEYA.

Patented Mar. 22, 1932 UNITED STATES PATENT OFFICE ALBERT E. MARSHALL,OF BALTIMORE, MARYLAND, ASSIGNOB TO CORNING GLASS WORKS, OF CORNING, NEWYORK, A CORPORATION OF NEW YORK vacuum 'rman AND monn'rme Applicationfiled April 21,

This invention relates to vacuum tubes and mountings therefor and moreparticularly to the arrangement of the elements through which contact isestablished between the tube 5 and the transmitting or receivingcircuit.

For some time engineers and others interested in improving thetransmission and reception of communications have recognized certaininherent faults in the vacuum tubes 0 and sockets commonly employed.These tubes are characterized by a cylindrical base, usually in the formof a metal shell which encloses a flat insulating body, from the bottomof which project four prongs constituting the terminals of the plate,grid and filament structure of the tube. These prongs form contacts bywhich their respective elements are connected to the other parts of thereceiving or transmitting circuit, and in some instances serve asanchors for holding the tube in place in its socket. The majority of thesockets employed rely on horizontally disposed springs, to make contactwith the prong tips, while other types use side wipe contacts toovercome the difliculties resulting from weak springs and tubes havingprongs of irregular length. The present standard vacuum tubes requiresockets which provide for the correct relative location of the prongs.This is accomplished 0 by enveloping the tube base and providing alocating device such as a bayonet lock. Without/such means it would bepossible, when inserting a tube into the socket. to make contact withthe wrong prongs, and since the filaments are usually built for 6 boltswhile the plate carries voltages up to 200 any wrong location of thetube in itssocket would very likely result in the plate voltage beingapplied to the filament, with disastrous effect upon the latter.

One difficulty with these types of tubes and sockets is that imperfectelectrical contact, between the contact members of the socket and theprongs, is frequently experienced, resulting in annoying vibration, lossof power and generally poor operation. Another serious difficulty withsuch tubes is'the close proximity and parallel relation of the plate andgrid terminal prongs to each other, which introduces undesirableelectrostatic capacity, and

1928. Serial No. 271,962.

' minimize this.

The object of my invention is to improve communication apparatus and toovercome the difficulties and disadvantages encountered 1n the use ofthe vacuum tubes now commonly employed.

Among its important features my invention embodies the wide separationof the grid and plate leads by which the electrostatic capacity efiectsare minimized, and the use of positively gripping contact members forengaglng the grid, plate and filament terminals so as to insure goodelectrical contact between the tube elements and the transmitting orreceiving circuit. These features will become more evident uponconsideration of the following specification taken in conjunction withthe accompanying drawings wherein:

Fig. 1 is a perspective view of a socket or mounting constructed inaccordance with this invention;

Fig. 2 is a bottom plan view of Fig. 1 with the metallic contactportions removed;

Fig. 3 is a transverse sectional view taken on the line 3-3 of Fig. 2;

Fig. 4 is an enlarged fragmentary sectional view taken on the line 4-4of Fig. 1;

Fig. 5 is an enlarged fragmentary sectional view taken on the line 55 ofFig. 1;

Fig. 6 is a side view in elevation of a vacuum tube for use inconjunction with the mounting herein described;

Fig. 7 is a bottom plan view of Fig. 6; and

Fig. 8 is a side view of a vacuum tube constructed in accordance withthis invention and supported by a modified form of mounting. the latterbeing shown in section.

Referring to the drawings in detail, a socket or mounting designatedgenerally 12, comprises a disk 13 of non-conducting material such asglass. This disk is provided with openings 14, 14a, 15 and 16, and atdiametrically opposite points with peripheral notches 17 for thereception of anchoring screws (not shown).

As illustrated in Fig. 1, the openings 15 and 16 are formed atdiametrically opposite l points near the periphery of the disk andreceive studs '18 to the upper ends of which are secured bifurcatedcontact springs 20.

5) are metallic bushings 24 which are formed with heads 25, the latterbeing received in countersinks 26 formed in the upper face of the disk13 in longitudinal alignment with the openings 14 and 14a. The lowerportions of the bushings are split as illustrated in the drawings toprovide yieldable gripping jaws in which the prongs of a vacuum tube areclamped. The lower ends of the openings 14 and 14a communicate withrecesses 27 for the reception of conductors through which current issupplied to the filament of the vacuum tube.

The vacuum tube with which the above type of socket is used, containsthe conventional grid, plate and filament structure all mounted withinthe customary glass envelope 28 to which is secured a base 29. Thelatter consists of a cylindrical body provided with a pair of spaceddepending prongs 30 and 30a to which the filament terminals areelectrically connected. Extending radially from the base aresubstantially ii-shaped contacts 31 and 32, the former of which iselectrically connected to the grid, while the latter forms the terminalof the plate. These contacts are arranged in diametrically opposed relation. and extend well beyond the periphery of the base 29 so that whenthe tube is in position, on the mounting, the contacts 31 and 32 willengage the contacts 20.

In the modification illustrated in Fig. 8,

y the socket 12 comprises a disk 13 which, like the disk 13, is formedwith openings to receive the grid and plate contact elements. Formed inthe upper face of the disk 13 is a recess, 33 for the reception of acushion 3d.

35 which register with the filament contact receiving openings 36 formedin the disk, and fitted in the openings 35 are contact bushings 25' bywhich contact is established between the filament of the vacuum tube andits power source. The interposition of a cushion between the tube baseand socket effect-ively reduces microphonic'efi'ects such as arefrequently experienced with uncushioned mountings. The grid and platecontact springs conform in structure to, and are s..- cured in theirrespective openings, in the same manner as the bifurcated contactsprings 29 above described.-

in use, the tube is placed in the socket by The latter is provided withcountersunk openings releases entering the prongs 30 and 30a into theopenings 14 and 140 respectively. Upon pressing the tube firmly intoplace, the V-shaped contacts 31 and 32 will enter between the respectivejaws of the bifurcated contact springs 20, forcing the same apart andforming good electrical contact therewith. In the meantime the prongswill frictionally wipe against the walls of the bushings 24 to insureproper contact therewith. Owing to the unsymmetrical location of thefilament contacts with relation to the grid and plate -contacts, properlocation of the tube in the socket is assured. Furthermore, danger ofburning out the filament is precluded, as in no position is it possibleto place the latter across the plate circuit. Wide separation of thegrid and plate terminals overcome much of the dificulty experienced withthe ordinary type of vacuum tube, as the electrostatic capacity betweenthese two elements is reduced to a minimum.

While in the foregoing there has been shown and described the preferredembodiment of this invention, it is to be understood that minor changesin the details of construction, combination and arrangement of parts maybe resorted to without departing from the spirit of the invention asdefined in the appended claims.

1 claim:

l. A vacuum tube mounting including a disk of insulating material havingdiametrically opposed peripheral notches, openings near its periphery indiametrically opposite relation and openings near its center instaggered relation, said disk also having recesses in one facecommunicating with the openings and extending to the periphery.

2. A. vacuum tube mounting comprising a disk of insulating materialhaving diametrically opposed peripheral notches, openings near itsperiphery in diametrically opposite relation and openings near itscenter in staggored relation, said disk also having recesses in one facecommunicatin with the openings and extending to the periphery, andcontacts mounted in the openings.

A vacuum tube mounting comprising a disk of insulating material havingdiametrically opposed peripheral notches, openings near its periphery indiametrically opposite relation and openings near its center in stageredrelation, said disk also having recesses in its lower face communicatingwith the openings, a depression in the upper face and a cushion fittedtherein.

ALBERT E. MARSHALL.

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